reposting a query about PVP/PVPP

Hello,
I suppose my query about the uses of PVP and/or PVPP failed to find a target in the cyberspace. I do need an answer/reference to it. So, here is the origininal question again:
" ...Can anybody point me to the reference(s) which deal(s) with the use of PVP or PVPP in the NA extraction using CTAB? Is their a difference in the outcome between the use of PVP or PVPP?"
Sincerely,
Hiranya.
Dr. Hiranya Sankar Roychowdhury
Plant Genetic Engineering Lab.
New Mexico State University
Las Cruces, NM 88003
Ph. (505) 646-5785
hroychow at nmsu.edu